Project 2, Mindfulness and Stress Arousal, extends the work of Project 1, the clinical trial of Mindfulness Based Stress Reduction (MBSR), by examining specific stress-related adaptive and maladaptive cognitive and affective mechanisms through which MBSR may influence neuroendocrine and autonomic nervous system activity. The hypotheses are based on Stress and Coping Theory (Lazarus & Folkman, 1984), which emphasizes the role of cognitive appraisal in shaping the psychological and physiological stress response. This framework is compatible with the principles of the MBSR program, which highlight the regulation of attention and perception as a way to reduce stress. Project 2 includes two studies. Study A will test hypotheses regarding the relationship between perceived stress and basal neuroendocrine activity (Specific Aim 1) and the extent to which the effects of MBSR on basal neuroendocrine activity are mediated by adaptive and maladaptive cognitive and affective pathways (Specific Aim 2). Subjects will include all the participants in the MBSR arm of Project 1 (N = 165) and participants in the wait-list control group (N=83). Psychological assessments will be made at baseline, post intervention, 6 months, and 12 months. Diurnal catabolic and anabolic hormones will be assayed at baseline, post intervention, and 12 months. In Study B, these same hypotheses will be tested in a controlled laboratory setting where participants will be exposed to an acute laboratory stressor (Trier Social Stress Test) post-intervention, while autonomic reactivity is assessed in additon to neuroendocrine reactivity (Specific Aim 3). The primary goal of Study B is to test whether people who take MBSR respond with a more adaptive physiological profile. Appraisal processes, and their attendant patterns of affective and physiological arousal, have also been linked to HIV disease progression. In Specific Aim 4, the relationship between adaptive and maladaptive arousal responses will be examined in relation to CD4+ T cell decline, HIV viral load, and depression. Project 2 will also provide data for Project 3 with which it can further explore the links between neuroendocrine response to both naturalistic and laboratory stress and immune system mediation.